Edwin asked in Food & DrinkCooking & Recipes · 1 decade ago

Why do you need to heat milk to make homemade yogurt?

All the homemade yogurt recipes I have found online say one must heat milk up to 180 degrees, then cool it, before putting it into a yogurt machine.

Why? If I don't heat the milk, will I become ill if I eat the yogurt? Or is it more a matter of the yogurt not thickening or setting properly? In other words, is it more of a physical health issue to heat milk, or a recipe issue?

7 Answers

  • 1 decade ago
    Favorite Answer

    Milk doesn't need to be "very very hot" to make yogurt, but it does need to be a little hot (around 110-120 F) just so that the bacteria fermenting the yogurt will eat up the milk sugars *quickly enough* not to take forever to incubate to the yogurt stage... it would still happen, it would just take a lot longer (and during that time, other bacteria could be introduced from the air and change the flavor/etc too).

    The main reason that milk is actually heated all the way to 185 F or so, is just so that the resulting yogurt will turn out thicker than if it hadn't been heated that high. At that temp, the whey proteins will denature and coagulate to enhance the viscosity and texture.

    You won't become ill if you don't heat the milk higher than 110 or so though because the milk has already been pasturized at some point to that high a temp, and you also won't be leaving your milk out or in the "danger zone of 40-140 F for too long. Also the fermentation will create an acidic environment which is a kind of preservative of its own.

    The "scalding" technique was traditionally done to kill the enzymes that caused milk to spoil before pasteurization came along..although some people do still drink "raw" milk.)

    So it's a "recipe issue" that has to do with wanting thicker yogurt** since most people are used to the store-bought yogurts which have had various gums and stabilizers/etc added to them to make them thicker (and increase unopened shelf life).

    **adding 1/2 c powdered milk to the liquid milk can help with that too, and not stirring the yogurt after it's set


    Diane B. (who heats her milk to 185F then holds it for 5-10 minutes before cooling and adding starter, but only as a preference)

  • 4 years ago

    Heating Milk For Yogurt

  • 1 decade ago

    I tried making yogurt once and it did not turn out. Not sure why, and I will try again.

    My guess is that heating the milk then cooling it before you add the active yogurt starter culture is so the growth is not slowed down by the cold milk. Bacteria like to eat and reproduce in a warm environment. May also be a throw back from when pasteurized milk was not commonly available and the instructions are also for people on farms or people that obtain raw milk.

    Think I will try making yogurt again then mozzarella cheese or cottage cheese after that.

  • 6 years ago

    Milk does not have to be heated to make yogurt. I have made yogurt from powdered milk, regular milk and now using raw milk. Why would I want to kill the good bacteria in the raw milk when that is what I want? Heating can mke it thicker but there are other ways to do that like adding powdered milk or unflavored gelatin without destroying the benefits of the milk epecially raw milk. The gelatin has other health benefits it will add also.

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  • Juju
    Lv 4
    1 decade ago

    Bacteria causes yogurt to thicken, if you don't heat it to kill the bad bacteria you will get a taste that is not right. You have to cool it down some before putting in the yogurt culture or you will kill the good bacteria.

  • 1 decade ago

    Its not a health issue its just that it wont work.

    Heating the milk up will start changing the enzymes and fats in the milk. Without heat they won't be activated and you wont have yogurt.

    Just heat it up, its not difficult.

  • 1 decade ago

    I'm guessing recipe. Why can't you just heat it up. It's really not that hard!

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